Writing an apology letter can help restore goodwill among your customers, clients, and partners.
If the letter is being sent as a hard copy, then it should be in the proper business format, otherwise, if the letter is being emailed, it should have an appropriate subject line and proper grammar.
We are deeply sorry about the shipping error that was made on your last order. We pride ourselves on delivering quality and timely service to all of our customers and were diapointed in ourselves when we were made aware of our mistake.
On, February 24, 2020, you placed an order and were expecting 60 bottles of our premium cleaner, but you received 60 bottles of our standard cleaner. There was an error in our description, which has been fixed. We realzie our error may have caused complications with the services that you offer to your customers.
We have expedited 60 bottles of our premium cleaner to you at no additional charge. You may keep our standard cleaner to use. We have added a 10% coupon for you to use on a future order to show that we value you as a customer and are truly sorry. We hope you can forgive us for our mistake and hope we can continue doing business with each other.